Trends in major and minor meteorological variables and their influence on reference evapotranspiration for mid Himalayan region at east Sikkim, India

Abstract： Estimation of evapotranspiration （ET） for mountain ecosystem is of absolute importance since it serves as an important component in balancing the hydrologic cycle. The present study evaluates the performance of original and location specific calibrated Hargreaves equation （HARG） with the estimates of Food and Agricultural Organization （FAO） Penman Monteith （PM） method for higher altitudes in East Sikkim, India. The results show that the uncalibrated HARG model underestimates ET0 by 0.35 mm day^-1 whereas the results are significantly improved by regional calibration of the model. In addition, this paper also presents the variability in the trajectory associated with the climatic variables with the changing climate in the study site. Non- parametric Mann-Kendall （MK） test was used to investigate and understand the mean monthly trend of eight climatic parameters including reference evapotranspiration （ET0） for the period of 1985 - 2009. Trend of ET0 was estimated for the calculations done by FAO PM equation. The outcomes of the trend analysis show significant increasing （p ≤ 0.05） trend represented by higher Z-values, through MK test, for net radiation （Rn）, maximum temperature （Tmax） and minimum temperature （Train）, especially in the first months of the year. Whereas, significant （0.01 ≥ p ≤0.05） decreasing trend in vapor pressure deficit （VPD） and precipitation （P） is observed throughout the year. Declining trend in sunshine duration, VPD and ET0 is found in spring （March - May） and monsoon （June - November） season. The result displays significant （0.01≤ p ≤0.05） decreasing ET0 trend between （June - December） except in July, exhibiting the positive relation with VPD followed by sunshine duration at the station. Overall, the study emphasizes the importance of trend analysis of ET0 and other climatic variables for efficient planning and managing the agricultural practices, in identifying the changes in the meteorological parameters and to accurately assess the hydrologic water balance of the hilly regions.

Effect of LASER on the Synthesis of Gold Nanoparticles with Reference to Geometries

Problem Statement: In the current study the effort was being made to investigate the effect of LASER light on the shape and geometries of Gold Nanoparticles. Light is an important parameter that plays significant role in the formation of nanoparticles;in this study LASER lights of selected wavelengths and colors have been used for the exposure of Gold Nanoparticles. The possibilities to manipulate the geometries of Gold Nanoparticles by altering the colors and wavelengths of LASER have been studied with reference to their efficacy against Culex quinquefasciatus. Approach: In the experimental setup four black boxes are used with no exposure to light sources. Three LASER with selected wavelengths and colors were fixed in the boxes at a specific angle, and then the nanoparticle solution was allowed to react. The micrographs of the Gold nanoparticles have been evaluated through the Transmission Electron Microscope (TEM). Results: The TEM images have shown formation of different shapes of nanoparticles due to exposure in different colors and wavelengths of LASER. Thus it explains that the wavelength and colour of the light plays a decisive role in the formation of the shapes and geometries of the nanoparticles.